Triple glazed windows significantly more expensive than their double glazed counterparts. A triple glazed casement window will cost around £110 more than a double glazed window. Triple glazing is appropriate for people replacing single glazing or old double glazing as it will enhance your home’s warmth, security and soundproofing significantly. For those replacing modern double glazing, however, you may find that the benefits are not noticeable enough to justify how much more you are paying.